Slack MCP Server with SSE Transport

Slack MCP Server with SSE Transport

A Model Context Protocol (MCP) server that provides Slack API integration using Server-Sent Events (SSE) transport. This server allows AI assistants to interact with Slack workspaces through a simple HTTP-based interface.

Features

• SSE Transport: Uses Server-Sent Events (SSE) instead of stdio, enabling communication over HTTP/HTTPS
• Slack API Integration: Provides access to essential Slack API functionality
• Simple Web Interface: Includes a basic web UI and health check endpoint
• Docker Support: Fully containerized with Docker for easy deployment
• TypeScript Implementation: Built with TypeScript for type safety and better developer experience
• Cross-Platform Compatibility: Works with any MCP client that supports SSE transport

Prerequisites

• Node.js 18 or higher
• Slack Bot Token with appropriate permissions
• Slack Team ID
• Docker (optional, for containerized deployment)

Environment Variables

Variable	Description	Default
SLACK_BOT_TOKEN	Your Slack Bot User OAuth Token (starts with xoxb-)	Required
SLACK_TEAM_ID	Your Slack Workspace/Team ID	Required
PORT	Port on which the server will run	3000

Setup Instructions

Obtaining Slack Bot Token and Team ID

1. Create a Slack App:

   • Visit the Slack Apps page
   • Click "Create New App"
   • Choose "From scratch"
   • Name your app and select your workspace

2. Configure Bot Token Scopes:

   • Navigate to "OAuth & Permissions" in your app settings
   • Add these scopes:
     • channels:history - View messages and other content in public channels
     • channels:read - View basic channel information
     • chat:write - Send messages as the app
     • reactions:write - Add emoji reactions to messages
     • users:read - View users and their basic information

3. Install App to Workspace:

   • Click "Install to Workspace" and authorize the app
   • Save the "Bot User OAuth Token" that starts with xoxb-

4. Get your Team ID:

   • Open Slack in a web browser
   • Once logged in, check the URL in your browser
   • The URL will be in a format like: https://app.slack.com/client/T01234567/...
   • Your Team ID is the string beginning with T (e.g., T01234567)

Local Development

1. Clone the repository
2. Install dependencies:

   npm install
   

3. Create a .env file based on .env.example:

   SLACK_BOT_TOKEN=xoxb-your-slack-bot-token
   SLACK_TEAM_ID=your-slack-team-id
   PORT=3000
   

4. Build the TypeScript code:

   npm run build
   

5. Start the server:

   npm start
   

For development with automatic reloading:

npm run dev

Docker Deployment

Using Docker Compose (Recommended)

1. Create a .env file with your Slack credentials as shown above
2. Build and run the container:

   docker compose up --build
   

Using Pre-built Image

docker run -p 3000:3000 \
  -e SLACK_BOT_TOKEN=xoxb-your-slack-bot-token \
  -e SLACK_TEAM_ID=your-slack-team-id \
  ghcr.io/dvelopment/slack-mcp-server-sse:latest

For more detailed Docker instructions, including publishing to GitHub Container Registry, see DOCKER.md.

Server Endpoints

• SSE Endpoint: /sse - Connect to this endpoint to receive SSE events
• Health Check: /health - Simple health check endpoint (returns {"status":"ok"})
• Home Page: / - Simple HTML page with information about the server

Available Slack API Tools

Tool Name	Description	Required Parameters
slack_list_channels	List public channels in the workspace with pagination	None (optional: limit, cursor)
slack_post_message	Post a new message to a Slack channel	channel_id, text
slack_reply_to_thread	Reply to a specific message thread in Slack	channel_id, thread_ts, text
slack_add_reaction	Add a reaction emoji to a message	channel_id, timestamp, reaction
slack_get_channel_history	Get recent messages from a channel	channel_id (optional: limit)
slack_get_thread_replies	Get all replies in a message thread	channel_id, thread_ts
slack_get_users	Get a list of all users in the workspace	None (optional: cursor, limit)
slack_get_user_profile	Get detailed profile information for a specific user	user_id

Connecting to the Server

Node.js Client Example

// Replace with your server URL
const SERVER_URL = 'http://localhost:3000/sse';

// Create EventSource to connect to the SSE endpoint
const eventSource = new EventSource(SERVER_URL);

// Handle connection open
eventSource.onopen = () => {
  console.log('Connected to SSE server');
};

// Handle messages
eventSource.onmessage = (event) => {
  console.log('Received message:', event.data);
  try {
    const data = JSON.parse(event.data);
    console.log('Parsed data:', data);
  } catch (error) {
    console.log('Raw message (not JSON):', event.data);
  }
};

// Handle errors
eventSource.onerror = (error) => {
  console.error('SSE connection error:', error);
  eventSource.close();
};

See the examples directory for complete client examples:

• examples/client.js - Node.js client example
• examples/browser-client.html - Browser client example

Using with Claude MCP Wrapper

To use this server with the Claude MCP wrapper:

claude_mcp_wrapper.sh -y docker run -i --rm -e SLACK_BOT_TOKEN -e SLACK_TEAM_ID mcp/slack

Or for an SSE-based connection:

claude_mcp_wrapper.sh -y http://localhost:3000/sse

License

MIT